MOTOROLA MPX12 User Manual
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SEMICONDUCTOR TECHNICAL DATA
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The MPX12 series device is a silicon piezoresistive pressure sensor providing a very
accurate and linear voltage output — directly proportional to the applied pressure. This
standard, low cost, uncompensated sensor permits manufacturers to design and add
their own external temperature compensating and signal conditioning networks.
Compensation techniques are simplified because of the predictability of Motorola’s single
element strain gauge design.
Features
• Low Cost
• Patented Silicon Shear Stress Strain Gauge Design
• Ratiometric to Supply Voltage
• Easy to Use Chip Carrier Package Options
• Differential and Gauge Options
Application Examples
• Air Movement Control
• Environmental Control Systems
• Level Indicators
• Leak Detection
• Medical Instrumentation
• Industrial Controls
• Pneumatic Control Systems
• Robotics
Figure 1 shows a schematic of the internal circuitry on the stand–alone pressure
sensor chip.
PIN 3
+ V
S
PIN 2
+ V
PIN 4
– V
out
out
X–ducer
0 to 10 kPa (0–1.45 psi)
35 mV FULL SCALE SPAN
(TYPICAL)
BASIC CHIP
CARRIER ELEMENT
CASE 344–15, STYLE 1
DIFFERENTIAL
PORT OPTION
CASE 344C–01, STYLE 1
NOTE: Pin 1 is the notched pin.
PIN NUMBER
1
Gnd
2
+V
out
3
V
4
–V
S
out
PIN 1
Figure 1. Uncompensated Pressure Sensor Schematic
VOLTAGE OUTPUT versus APPLIED DIFFERENTIAL PRESSURE
The differential voltage output of the X–ducer is directly proportional to the differential
pressure applied.
The output voltage of the differential or gauge sensor increases with increasing
pressure applied to the pressure side (P1) relative to the vacuum side (P2). Similarly,
output voltage increases as increasing vacuum is applied to the vacuum side (P2)
relative to the pressure side (P1).
Senseon and X–ducer are trademarks of Motorola, Inc.
Motorola Sensor Device Data
Motorola, Inc. 1997
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MAXIMUM RATINGS
Rating Symbol Value Unit
Overpressure
Burst Pressure
Storage Temperature T
Operating Temperature T
(8)
(P1 > P2) P
(8)
(P1 > P2) P
max
burst
stg
A
75 kPa
100 kPa
–40 to +125 °C
–40 to +125 °C
OPERATING CHARACTERISTICS (V
Characteristic
Differential Pressure Range
(5)
(2)
(3)
(6)
(10% to 90%) t
(9)
Supply Voltage
Supply Current I
Full Scale Span
(4)
Offset
Sensitivity ∆V/∆P — 5.5 — mV/kPa
Linearity
Pressure Hysteresis
Temperature Hysteresis
Temperature Coefficient of Full Scale Span
Temperature Coefficient of Offset
Temperature Coefficient of Resistance
Input Impedance Z
Output Impedance Z
Response Time
Warm–Up — — 20 — ms
Offset Stability
(1)
(5)
(0 to 10 kPa) — — ± 0.1 — %V
(5)
(–40°C to +125°C) — — ± 0.5 — %V
(5)
= 3.0 Vdc, TA = 25°C unless otherwise noted, P1 > P2)
S
Symbol Min Typ Max Unit
P
OP
V
S
o
V
FSS
V
off
— –0.5 — 5.0 %V
(5)
(5)
TCV
FSS
TCV
off
TCR 0.21 — 0.27 %Zin/°C
in
out
R
— — ±0.5 — %V
0 — 10 kPa
— 3.0 6.0 Vdc
— 6.0 — mAdc
45 55 70 mV
0 20 35 mV
–0.22 — –0.16 %V
— ±15 — µV/°C
400 — 550 Ω
750 — 1250 Ω
— 1.0 — ms
MECHANICAL CHARACTERISTICS
Characteristic Symbol Min Typ Max Unit
Weight (Basic Element, Case 344–15) — — 2.0 — Grams
Common Mode Line Pressure
NOTES:
1. 1.0 kPa (kiloPascal) equals 0.145 psi.
2. Device is ratiometric within this specified excitation range. Operating the device above the specified excitation range may induce additional
error due to device self–heating.
3. Full Scale Span (V
minimum rated pressure.
4. Offset (V
5. Accuracy (error budget) consists of the following:
• Linearity: Output deviation from a straight line relationship with pressure, using end point method, over the specified
• Temperature Hysteresis: Output deviation at any temperature within the operating temperature range, after the temperature is
• Pressure Hysteresis: Output deviation at any pressure within the specified range, when this pressure is cycled to and from the
• TcSpan: Output deviation at full rated pressure over the temperature range of 0 to 85°C, relative to 25°C.
• TcOffset: Output deviation with minimum rated pressure applied, over the temperature range of 0 to 85°C, relative
• TCR: Zin deviation with minimum rated pressure applied, over the temperature range of –40°C to +125°C,
6. Response Time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when subjected to
a specified step change in pressure.
7. Common mode pressures beyond specified may result in leakage at the case–to–lead interface.
8. Exposure beyond these limits may cause permanent damage or degradation to the device.
9. Offset stability is the product’s output deviation when subjected to 1000 hours of Pulsed Pressure, Temperature Cycling with Bias Test.
) is defined as the output voltage at the minimum rated pressure.
off
(7)
) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the
FSS
pressure range.
cycled to and from the minimum or maximum operating temperature points, with zero differential pressure
applied.
minimum or maximum rated pressure, at 25°C.
to 25°C.
relative to 25°C.
— — — 690 kPa
FSS
FSS
FSS
FSS
FSS
/°C
2
Motorola Sensor Device Data
TEMPERATURE COMPENSATION
Figure 2 shows the typical output characteristics of the
MPX12 series over temperature.
The X–ducer piezoresistive pressure sensor element is a
semiconductor device which gives an electrical output signal
proportional to the pressure applied to the device. This device uses a unique transverse voltage diffused semiconductor strain gauge which is sensitive to stresses produced in a
thin silicon diaphragm by the applied pressure.
Because this strain gauge is an integral part of the silicon
diaphragm, there are no temperature effects due to differences in the thermal expansion of the strain gauge and the
diaphragm, as are often encountered in bonded strain gauge
pressure sensors. However, the properties of the strain
gauge itself are temperature dependent, requiring that the
device be temperature compensated if it is to be used over
an extensive temperature range.
Temperature compensation and offset calibration can be
achieved rather simply with additional resistive components,
or by designing your system using the MPX2010D series
sensor.
Several approaches to external temperature compensation over both – 40 to +125°C and 0 to + 80°C ranges are
presented in Motorola Applications Note AN840.
LINEARITY
Linearity refers to how well a transducer’s output follows
the equation: V
pressure range (Figure 3). There are two basic methods for
calculating nonlinearity: (1) end point straight line fit or (2) a
least squares best line fit. While a least squares fit gives the
“best case” linearity error (lower numerical value), the calculations required are burdensome.
Conversely, an end point fit will give the “worst case” error
(often more desirable in error budget calculations) and the
calculations are more straightforward for the user. Motorola’ s
specified pressure sensor linearities are based on the end
point straight line method measured at the midrange
pressure.
out
= V
+ sensitivity x P over the operating
off
80
70
60
50
40
OUTPUT (mVdc)
30
20
10
0
0
PSI
kPa
VS = 3 Vdc
P1 > P2
0.3
2.0
0.6
4.0
PRESSURE DIFFERENTIAL
+25°C
0.9
6.0
–40°C
+125°C
1.2
8.0 10
SPAN
RANGE
(TYP)
OFFSET
(TYP)
1.5
70
60
50
40
30
OUTPUT (mVdc)
20
10
0
0 MAX
LINEARITY
ACTUAL
THEORETICAL
PRESSURE (kPA)
Figure 2. Output versus Pressure Differential Figure 3. Linearity Specification Comparison
WIRE BOND
SILICONE
DIE COAT
DIE
P1
STAINLESS STEEL
METAL COVER
EPOXY
CASE
SPAN
(V
)
FSS
OFFSET
(V
)
OFF
P
OP
LEAD FRAME
Figure 4. Cross–Sectional Diagram (not to scale)
Figure 4 illustrates the differential or gauge configuration
in the basic chip carrier (Case 344–15). A silicone gel isolates the die surface and wire bonds from the environment,
while allowing the pressure signal to be transmitted to the silicon diaphragm.
The MPX12 series pressure sensor operating characteris-
Motorola Sensor Device Data
RTV DIE
P2
BOND
tics and internal reliability and qualification tests are based
on use of dry air as the pressure media. Media other than dry
air may have adverse effects on sensor performance and
long term reliability. Contact the factory for information regarding media compatibility in your application.
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